1. Field of the Invention
The present invention relates generally to a wafer collecting apparatus, and more particularly to a wafer collecting apparatus which collects a number of wafers, which have been sliced at the same time by a wire saw, one by one from a slice base which holds the wafers.
2. Description of Related Art
As shown in FIG. 5, when a wire saw 1 slices an ingot In which is made of silicon, etc. which is material for a semiconductor device, the ingot In is inclined at a predetermined angle .theta. with respect to a wire row so that the wafers W can be in a predetermined crystal orientation. Therefore, several wafers W at both ends of the ingot cannot be round. They may be crescent-shaped or chipped at the bottom end thereof.
A number of wafers W, which have been sliced at the same time, are held in a slice base S (batch wafers), and the wafers W are separated from the slice base to be individual wafers. A special separating machine is used to separate the wafer W from the slice base. Since the wafers which are not circular (inferior wafers) cannot be sold on the market, an operator needs to recognize the inferior wafers before the wafers W are set in the separating machine or after the wafers W are separated from the slice base S.
It is inefficient and unproductive because the operator has to recognize and remove the inferior wafers among the sliced wafers every time the ingot is sliced.